Process of treating gases



' 1170 Drawing.

um-T D TATES PATENT oFiuCE;

:osnrn c. w. rnaznn, or BALTIMORE, mARYLAnmAItTnUn IB. LAMB, or wasznte on, DISTRICT or COLUMBIA, AND DAVID R. MERRILL, or NEWARK, NEW JERSEY.

success or TREATING eases.

To all whom it may concern Be it known that we, JOSEPH C. W.

FRAZER, ARTHUR B. LAMB, and DAVID R.

. MERRILL, citizens of the United States, and

residing at Baltimore, Maryland, Washington, District of Columbia, and Newark, New Jersey, respectively, have invented certain new and useful Improvements in Processes of Treating Gases, of which the'following is a specification.

The present invention. relates to processes of purlfication of gases by removal therefrom of oxidizable constituents and more specifically. to processeswherein the oxidiz able constituents are combined with oxygen to produce compounds which are'innoxious,

or which may be condensed or dissolved, or combined chemically with suitable reagents and thus removed from the reaction products.

This process comp-rises the catalytic removal of catalytic poisons from gases whichare subsequently subjected to the'action of catalysts. In this way the danger of poisoning or destroying the eificiency of catalysts is removed or substantially avoided.

The'invention comprises the passing of Y the gases through a sorbent oxidizing catalyst small, bein without such admixture.

' at a low temperature, the gases being previously mixed with the necessary quantity of air or oxygen when the amount of impurities is large and when the amount is acetylene, ammonia, etc, and to accomp ish such removal I at low temperatures. In other words, it might be said that one of the objects of the invention is to provide a process whereby combustible mixtures may be- 1 freed by selective oxidation of certain of the constituents.

v operating It has been found that certain compounds or mixtures containing same when prepared in suitable condition have the property of oxidizing most oxidizable gases and vapors at lowtemperatures, in certain instances, as low as room temperature andlower. When .at room tem eratures the gases are usua 1y first dried. S ueh compounds'are' Specification of Letters1atent. P t nted May 30,1922. Application filed February 12, 1919. Serial No. erases.

copper oxide, basic copper carbonate, mixtures of copper oxide and manganese dioxide, of copper oxide and cobalt oxide, of manganese dioxide and ferric oxide, and others. It may be stated as a general rule that .a mixture of metallic oxides consisting of-two or more oxides, one being polyvalent' and the other monoor di-valent, Wlll pro-- duce the desired oxidation, when properly prepared. The catalysts are active from the start even when operating at low temperatures. In other words when the gases are broughtv in contact with the catalysts the' oxidation begins at once.

The choice of the material to be used in any particular oxidation depends on the ease in a very finely divided state, preferably by precipitation, substantially complete removal of the impurities, such as-the excess of precipitant, collection of the material, thorough kneading in order to very intimately mix the constituents, formation into a more or less dense cake, and .drying of the cake at low temperatures.

Specific examples of the preparation of a copper oxide catalyst and one composed of copper oxide or carbonate and manganese oxide areas follows: 7

' Example 1: Copper oxide;

Copper oxide is prepared from copgpr sul,fate and sodium hydroxide by rapi y mixing these two reagents in hot concentrated solutions in order to finely divided precipitate. his precipitate is then thoroughly washed by decantation,

collected on a' filter, thoroughly kneaded, compressed if desired, and dried at 120 to 130 C. The resultant cake is then crushed to a suitablesize and is then ready for use.

In using this copper oxide catalyst for the elimination of arsine and phosphine from acetylene or" ammonia the gas mixture is passed over or through the catalyst, along with suflicient. oxygen to combine with the to These methods of preparation inroduce a very Q... arsine and phosphine, at a temperaturehot exceeding 50 6 The twoimpurities will be ammonia. g v

Example 2': Copper manganese.

- Copper oxide or carbonate, repared as in,

Example 1, is mixed, preferab y before drying, with thoroughly washed manganesedioxide prepalged by the interaction of potassiumpermang'anate and manganese sulfate in-strong surfuric acid and subsequentdiluiiion, is collected on a filter, thoroughly.

kneaded, submitted 'to compression, if de-.v

sired, dried at a low temperature, and ground or crushed to a suitable size. It is then ready for use.

g In using this material for the separation of carbon monoxide from hydrogen, for example, the' impure hydrogen is mixed with sufficient oxygen to combine with the carbon monoxide present and provide a slight excess and the mixture afterbeing dried is temperature.

passed over or through the catalyst at room The carbon monoxide willbe completely oxidized with no appreciable action on the hydrogen. In case the impure hydrogen contains much water vapor or if it is not suitable to dry the gases before treatment, the'temperature of the catalyst may be raised to 75, to 110 (1., with complete removal of the carbon monoxide without appreciable quantities of the hydrogen being lost.

Other mixtures such as ferric oxide, man-- ganese dioxide,'bismuthic oxide, and copper oxide may be used if properly prepared as indicated.

" In using the material prepared in the manner indicated for the removal of small quantities of arsine and phosphine from gases, it is not necessary to add to the gas under treatment the amo'unt'of oxygen nec- I essary to oxidize these impurities, as the material is a sufliciently active oxidizing agent to accomplishthe oxidation at ordinary temperatures b means of the oxygen combined therein. f course, in such cases the material is not catalytic in'the ordinary meaning of the term.

' The'present invention is not limited to the specific details set forth in the foregoin ex amples which should be construed as.1 lus jtrative and not by way of limitation, and in .view of the numerous modifications which -may be eflected therein without departing from the spirit and scope of this invention, it is desired that onlyvsuch. limitations be imposed as are indicated inv claims. I I

1. The process ofremoving CO from gases the appended containing H which comprises causing the CO to combine with added 0' in the presence of a solidfcatalyst at 'a'temperature below 2. The process of treating gases. contain- C completely removed from the acetylene or of a metallic oxide as catalyst at a temperature below'100 C.

3..The process of removing CO from gases containing H which comprises causing in and G0 which comprises causing the: to combine with added 0 in the presence the CO to combine with added 0 in the presence of a solid catalyst and a promotor at atemperature below 100 C. I 4. The process of-removing CO from-gases containing H which comprises causing the CO to combinewith added 0 in the presence of a mixture of iron oxide with another metallic oxide as catalyst at a temperature below 100 C. p p .5. The process. of removing from an oxidizable gas impurities that are more readily I oxidized which comprises passing the gas tures below 100 C.-and.' causing oxidation of the impurities without substantial oxidation of the H.

' 8. The process ofremoving oxidizable imurities from H which comprises passing the i. into contactwith a catalyst at ordinary- .room temperatures and causing oxidation of the impurities without substantial oxidation oftheH."

'9. The process of removing from an oxidizable gas impurities that are more readily oxidized which comprises passing the gas in admixture with su'flicient as comprising free oxygen to .oxidize the impurities into contact with a, sorbent catalyst at tempera-' .tures below 100 C., and causing oxidation'of the impurities without substantial oxidation of the oxidizable gas.

dizable gas impurities that are more; readily oxidized which comprises passing the gas in admixture with sufficient gas comprising free oxygen to oxidize the impurities, into room temperatures and causing oxidation of the impurities without substantial oxidation i of the oxidizable gas.

11. The process of removing oxidizable impurities from H which comprises passing -the H admixed with suiiicient gas comprising .free oxygen to oxidize the impurities, into contact with a catalyst at temperatures below 100 C., and causing oxidation of the 10. The processor removing from'an oxiv contact with a sorbent catalyst at ordinary impurities without substantial oxidation of the H.

12. The-process of separating from oxidizable gases impurities that are morev readily oxidized which comprises bringing about at temperatures below 100 7., the selective oxidationof the impurities by means of a catalyst composed of one or more-metal oxides in extremely finely divided condition.

13. The process'of separating from oxidizable gases impurities that are more readily oxidized which comprises bringing about at ordinary room temperatures the selective oxidation of the impurities by means of a catalyst composed of one or more metal oxides in extremely finely divided condition.

14:. The process of purifying H whichcomprises oxidizing the impurities in the. presence of an oxidizing catalyst at temperatures below 100 C.

15. The process of removing CO from gases or mixtures of gases which comprises passin the gas or mixture of gases into contact with a catalyst below'100. G. and causing selective oxidation of the CO.

16. The process of removing CO from gases or mixtures of gases which com.- prises passing the gas or mixture of gases in admixture with sufficient gas comprising free oxygen to oxidize the CO into contact with a .catalyst at temperatures below 100 C. and causing selective oxidation of the CO.

17. The process of removing CO from gases I dized, subjecting said gases to the action of catalysts at ordinary room temperatures. I

19. In a process of removing from gases catalytic poisons that are more readily oxidize subjecting said gases to the action of catalysts at temperatures below 100 C.

Y 20. In a process of catalytically removing from gases catalytic poisons that are more readily oxidized, effecting at temperatures below 100 C. selective oxidation of said poisons by means of a catalyst composed of one or more metal oxides in extremely finely divided condition.

21. In a process of catalytically removing from gases catalytic poisons that are more readily oxidized, efi'ecting at ordinary room temperatures selective oxidation of said poisons by means of a catalyst composed of one or more metal oxides in extremely finely divided condition.

JOSEPH C. W.-'FRAZEB-.

' ARTHUR B. LAMB.

DAVID R. MERRILL. 

